Rio Tinto, Spain

Created by Sarah Bordenstein, Marine Biological Laboratory

Spain's Rio Tinto is characterized by deep red water that is highly acidic (pH 1.7—2.5) and rich in heavy metals. Over 5000 years of mining pollution have contributed to the river becoming an extreme environment, although the presence of chemolithotrophic organisms, such as iron-oxidizing bacteria and sulfur-oxidizing bacteria, are thought to be the true culprits to the river's condition. Home to many unusual organisms, the most remarkable findings to date may be the unexpected degree of eukaryotic diversity in the acidic water. The diversity of these eukaryotes, both alkaliphilic and toxitolerant, is much greater than that of the prokaryotes, thus challenging beliefs that extreme environments are always dominated by Eubacteria and Archaea.

The Rio Tinto holds a significant role in history as the birthplace of the Copper Age and Bronze Age. The first Rio Tinto mines were developed in 3000 b.c. by the Iberians and Tartessans. Tales of mineral wealth (gold, silver, and copper) drew the Phoenicians (2800 b.p.—2600 b.p.) and then the Romans (2000 b.p. - 1800 b.p.), who made some of the first coins from Rio Tinto's silver and gold. Other cultures, including the Visigoths (1600 b.p.—1300 b.p.) and the Moors (1300 b.p. to 500 b.p.), eventually abandoned the mines. The mines were rediscovered by Spain in 1556 and reopened in 1724, only to be sold to the British in 1871. They are now one of the most important sources of copper and sulfur in the world.

The origin of Columbus' 1492 expedition, the Rio Tinto is still creating history. It is now an expedition target for the Mars Analog Research and Technology Experiment (MARTE). MARTE is drilling for core samples and testing satellite links from Rio Tinto in preparation for remote robotics that may one day survey Mars. Thought to be a close analog to that of the Martian subsurface, Rio Tinto's extreme environment could also represent a unique biological setting to explore sulfur-based life on Europa. Therefore, understanding the extremophiles that live here contributes to our search for extraterrestrial life.

Rio Tinto Collections

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